The project is developing methods for precise study of genetic and geneticbiochemical processes in mammalian somatic cells, and applying these to the understanding of developmental processes in health and disease. The current efforts in this program are aimed at the production of additional gene mutations, characterizing and identifying their specific biochemical effects; production of specific hybrids permitting localization of the genes studied on the human chromosome; identifying specific cell surface antigens and characterizing their genetic-biochemical action; and identification of genetic regulatory mechanisms in normal differentiation processes, and in developmental diseases.